Pump for street-car brakes.



U Patentedluly 18,1899.

No. 629494. Y Y

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ruim Fon snaar en BRAKES. v (Applcltinn mld In'. l1, 1899.) -I

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i UNITED. STATES ,PATENT OFFICE.

VILLIAM F. KNELL, OF BATTLECEEK, MICHIGAN.

PUMP Fou 'STRE v2LT-CAR BRAKES.

SPECIFICATION forming' part of Letters Patent N o. 629,194, dated July18, 1899.

Application and nach 1i, 1899.

To all whom it may concern;

Be it known that I, WILLIAM F. KNELL, a citizen of the United States,residing at Battle Creek, in the county of Calhoun and State ofMichigan, have invented' a new and useful Street-Car Brake, of which thefollowing is a speciiication.

This invention relates to brakes for streetcars, and more. especially tothat class of car- 1o brakes in which the brakes are actuated to stopthe car by air-pressure stored up by a 4pump actuated from the car-axle.In such brakes it has been customary to provide a governor, or it mightbe called a safetyvalve, set to blow off at any desired pressure and tocontinuously work the pump against such pressure as long as thatpressure existed in the reservoir. This resulted in agreat loss ofpower; and it is the primary object of the 2o present invention toprovide brake-operating mechanism which will be edective in operationand'in which the pressure is at once relieved in the pump when therequired pressure exists in the reservoir.`

A further object of the invention isv to pro# vide the pump withimproved lubricating mechanism.

With this object in view my invention consists in the improvedconstruction, arrange- 3o ment, and combination of parts hereinafterfully described and 'afterward specifically pointed out in the appendedclaim.

- In order that others skilled in the art to which my invention mostnearly appertains y may make and use the same, I will now proceed todescribe its construction and operation, having reference to theaccompanying drawings, forming part hereof, in which-- A Figure 1 is-acentral longitudinal sectional 4o view through the car-axle andconnecting mechanism, the air-reservoir being shown in elevation, theparts. being illustrated in positions which they'assume while the air inthe reservoir is under a pressure less than that at which the governoris set. Fig. 2 is a simi.-

lar View showing the check-valves and governor in the positions theyassume as soon as the required'pressure exists in the reservoir.

Like numerals of reference mark the same 5o parts in both figures ofthedrawings.

Referring to the drawings by numerals, 5 indicates the car-axle; 6, apinion thereon; 7, a

Serial No. 708,706. (No model.)

crank-shaft parallel with the axle and driven therefrom by means of agear-wheel S, `meshing with pinion 6. These parts are inclosed in acasing 9, which also acts as an oil-reservoir. A crank-pin 10 ongear-wheel S carries one end of a pitman 11, the opposite end beingpivoted to the valveless piston 12, adapted to reciprocate in apump-cylinder 13. The pitman 11 is grooved from end to end in its upperface at 14, so that when in lits rotation the .crank-pin` and the innerend of the pitman are submerged in oil carried in casing 9` a portion ofthe oil will be carried up in groove 14 and caused to run down in saidgroove to the piston and lubricate it and the pivot of the pitman. o p IY 15 indicates the inlet for air to the pump, it being provided withinward-opening checkvalve 16. The pipes 17 18 are the outlets throughwhichthe air from the pump passes andareprovided withoutward-openingcheckvalve 19.

2O indicates the'reservoir into which the air is pumped, and 21 a pipeleading therefrom to the brake-cylinder.

Ordinarily at some point between the reservoir and the brakeeylinder agovernor or safety-valve is placed, which when the required pressure isattained in the reservoir will blow om With such a device the pump atits instroke will draw in air through inlet 15, and in its outstroke,having no other escape, will be forced into and through the reservoirand blow off through the safetyvalve or governor. 'This of courseamounts to a resistance to e'ach outstroke of the piston equal* to theVpressure at which the safetyvalve or governor is set and the waste ofthat much power at each revolution of the crank-shaft. As before stated,the primary object of my invention is to avoid this Waste of power, andin carrying out my invention I dispense with the ordinary safety-valveor governor and substitute the following meehansmzi 22 indicates abranch pipe leadingfrom pipe 17 to a small upright governor-cylinder 23,erected upon and communicating with inlet 15. In the cylinder 2 3 is apiston-head 24,

upheld by a spring 25, to which piston-head 'is attached a rod 26, whichwhen spring 25 is compressed will project into inlet 15 in the l IOOrear of check-valve 16. The spring 25 is of a strength just sufcient toresist all pressure below that required in the reservoir.

While the pressure in the reservoir is be 10W the required point, thepump will act as before described and the piston-head 24 be held up bythe spring 25, keeping the pistonrod 26 out of the Way of check-valve16. As soon, however, as the required pressure is attained in thereservoir the next outstroke of the pu mp piston-head will force airthrough pipes 17 and 22 and force the piston-head 24 down, compressingspring 25 and causing piston-rod 26 to project into inlet 15 behindcheck-valve 16, and to hold the check-valve open, as shown in Fig. 2. Solong as the pressure is maintained in the reservoir this condition willbe maintained, and the pump in its rcciprocations will simply take inand discharge air around check-valve 15, having no resistance toovercome. As soon as the pressure in the reservoir becomes less than theforce of spring 25 the pin 26 will be raised, leaving the check-vaive 16free and permitting the pump to resume its normal functions.

The operation of my invention and the advantages attending its usewillvbe readily apparent from the foregoing, and While I haveillustrated what I consider to be efficient means for carrying it out Ido not restrict myself to the exact constructions shown, as

What I claim to be new, and desire to secure by Letters Patent of theUnited States, is-

The combination with the valveless piston, of the cylinder havingdischarge and inlet openings in its head, an outward-opening check-valvein the discharge-opening, the inletpipe secured in the inlet-opening andformed as a valve-seat at its inner end, avalve adapted to said seat andto open inwardly, a stern for the valve extending' into the inletpipe, aperforated piston-head at the outer end of the valve-stem7 agovernoncylinder mounted upon and communicating with the inlet-pipe, aspring-supported piston head and rod in the govern or,the rod beingadapted to project transversely into the inletpipe outside of and in thepath of the valve-steinv when the pressure exceeds the strength of thespring, a curved pipe communicating between the discharge-opening andthe governorcylinder, and a pipe leading from the curved pipe to theair-reservoir, substantially as described.

WILLIAM F. KNELL. Witnesses:

F. W. DUNNING, CHARLES H. WHEELOCK.

